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Synthesis for organometallic cyclometallated transition metal complexes

a transition metal complex and organometallic cyclometallate technology, applied in the field of organometallic synthesis, can solve the problems of unstable and difficult handling of lithiated organic materials, low yield, solvent and the related 2-methoxy-ethanol are not desirable for practical use, etc., to achieve the effect of controlling the yield of desired isomers and improving the yield

Active Publication Date: 2005-03-22
GLOBAL OLED TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The process provides better yields and control of desired isomers.

Problems solved by technology

These procedures suffer from low yields, as well as the relative instability of and difficulty in handling lithiated organic materials.
This particular solvent and the related 2-methoxy-ethanol are not desirable for practical use due to adverse health effects.
But this process requires a large excess of a ligand since it is employed as the solvent, thereby either consuming valuable material or necessitating a process to recover excess ligand.
But this process often yields less-desireable meridional isomers or mixtures of the facial and meridonal isomers of the tris-cyclometallated complexes.
However, this procedure is inconvenient for facial isomers as it necessitates finding exact conditions for the reaction of each ligand.

Method used

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  • Synthesis for organometallic cyclometallated transition metal complexes
  • Synthesis for organometallic cyclometallated transition metal complexes

Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of fac-tris(2-phenylpyridinato-N,C2′)iridium(III)

K3IrBr6 (7.75 g, 9.82 mmol) was placed in a 200 mL flask with 75 mL 2-ethoxyethanol, 25 mL water, and 2-phenylpyridine (4.2 mL). The mixture was freeze-thaw degassed, and then refluxed for 4 hrs under nitrogen atmosphere during which time a yellow-orange precipitate appeared. After cooling, the precipitate was filtered, washed with 1 N HBr(aq), then water, and dried. Yellow tetrakis(2-phenylpyridine-N,C2′)(μ-dibromo)diiridium(III) (5.018 g) was collected (88% yield based on iridium). This intermediate material was used without further purification in the subsequent step.

Tetrakis(2-phenylpyridine-N,C2′)(μ-dibromo)diiridium(III) (0.960 g) and silver trifluoroacetate (0.54 g) were placed in a 100 mL flask. 1,2-Propanediol (35 mL) and 2-phenylpyridine (0.75 mL) were added and the mixture was freeze-thaw degassed and then refluxed under nitrogen for 5 hours. After cooling, the mixture was poured in air into 150 mL 1 molar HBr(a...

example 2-7

Additional Preparations of fac-tris(2-phenylpyridinato-N,C2′) iridium(III)

Examples 2 thru 7 were carried out in a similar manner to Example 1 except the solvent was changed as listed in Table 1. An additional difference for Examples 3 and 5 was that iridium(III) chloride hydrate was used as the starting material, and hence the intermediate formed in an analogous manner was tetrakis(2-phenylpyridine-N,C2)(μ-dichloro)diiridium(III). The results shown in Table 1 show that the process with solvents of the invention provide higher yield and better isomeric purity than comparison examples using other solvents, including those commonly found in the prior art of cyclometallation reactions. Example 2 compared to Example 3 further shows that while iridium chloride complexes may be used in the invention as starting materials, better yields may be obtained with the bromide complexes as starting materials.

TABLE 1MerExampleYieldIsomerExampleTypeHalideSolvent(%)(%)1InventionBr1,2-Propanediol91Trac...

example 8

Additional Preparation of fac-tris(2-phenylpyridinato-N,C2′) iridium(III)

This example was also carried out in a similar fashion to example 1, except the solvent was 1,3-propanediol. The yellow precipitate collected was dissolved in dichloromethane and filtered to remove insoluble silver and / or silver salts, and then precipitated by evaporating the solvent. The yield was 92% of tris(2-phenylpyridinato-N,C2′)iridium(III), of which the majority was the facial isomer and only 1.2% was identified as the meridional isomer.

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Abstract

Disclosed is a process for forming an organometallic cyclometallated iridium compound comprising reacting an iridium halide complex with a silver salt and excess organic cyclometallating ligand in a diol solvent. The process provides better yields and control of desired isomers.

Description

FIELD OF THE INVENTIONThis invention relates to the field of organic synthesis and to a process for forming organometallic cyclometallated complexes of Ir(III) comprising the step of reacting a halide-containing complex of the metal with a silver salt and a heterocyclic organic ligand compound capable of forming an organometallic cyclometallated complex and in a solvent comprising an organic diol.BACKGROUND OF THE INVENTIONOrganometallic cyclometallated complexes of transition metals (e.g. rhodium, iridium, platinum) have become useful materials because of their photophysical and photochemical properties. One especially important application of these compounds are as phosphorescent dopants in Organic Light-Emitting Diodes because of their strong emission from triplet excited states (M. A. Baldo, et al, Appl. Phys. Letters, 75, 4 (1999)). An important class of phosphorescent organometallic cyclometallated complexes contain ligands that are at least bidentate wherein one coordination ...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C07F15/00
CPCC07F15/0033C07F15/00
Inventor DEATON, JOSEPH C.PARTON, RICHARD L.
Owner GLOBAL OLED TECH
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